Duffy, who signed a five-year, $65-million extension with the Royals before the 2017 season, apparently isn't interested in being traded, as he made clear in his most recent tweet after learning his name came up in trade rumors.
The Royals, however, appear to be moving in the direction of a rebuild, with Eric Hosmer, Lorenzo Cain, Mike Moustakas, and Alcides Escobar potentially leaving via free agency, and trading Duffy's salary might relieve them of financial restrictions.
The 28-year-old was marvelous for Kansas City in 2016, going 12-3 with a 3.51 ERA in 42 appearances, including 26 starts.
Last season, his win total dropped to nine, his ERA rose from 3.51 to 3.81, and his strikeouts per nine dropped from 9.4 to 8.0 in 24 starts.
The Orioles had the worst ERA of any starting rotation (5.70) in MLB last season.